I think this is one of my own favorite projects of all time! It's 2 continuous servos connected to a lipo battery powered esp8266 that hosts a webpage with a remote control. I spent more hours than you can imagine playing with it. https://www.youtube.com/watch?v=YUY0712q7UU
One of my favorite games when I was a young child was a bottle cap race. Looking back, the realisation that anywhere I would go I could find the toy and the track could be literally anything I could get away with (even the absence of track is a track design) was very important. So much that today I work for a company that has the moto "The World is a Construction Kit".
I think this project is my grown-up, wealthier version of this childhood memory. I made so many tracks and little vehicle designs (especially tire design, that ended up to be more important than I anticipated):
https://www.youtube.com/watch?v=wHZdDi59iDs
https://www.youtube.com/watch?v=JVZBXbz1MTU
https://www.youtube.com/watch?v=1xfpP4DiD-k (little house <3)
https://www.youtube.com/watch?v=BAb8MPA5VQ4
Yesterday a friend showed me this project they made at the school he worked in China and I was so happy to see my code running and being part of this wacky project learning <3 https://www.youtube.com/watch?v=zBhs7OMZpNU&feature=emb_title